Drowning, haemodilution, haemolysis and staining of the intima of the aortic root-- preliminary observations.

In order to demonstrate that hyponatraemia due to haemodilution occurs within the left ventricle following freshwater drowning, and to determine whether lysed blood resulting from left ventricular haemodilution may cause staining of the aortic intima, the following studies were undertaken. Measurements of left ventricular sodium levels were performed in 74 consecutive coronial cases where death was attributed to drowning, consisting of 44 and 30 deceased who were believed to be victims of freshwater and saltwater drowning, respectively. Left ventricular sodium levels differed significantly between the two groups (p<0.001), with a range of 93-147 mmol/L in freshwater drowning (mean=117+/-14.2 mmol/L) and 123-183 in saltwater drowning (mean=153+/-14.4 mmol/L). In addition, the mean sodium level of 117 mmol/L in freshwater drowning was significantly lower than the standard range of 137-145 mmol/L. In a second study, portions of aorta and pulmonary trunk from a euthanised pig were soaked in lysed blood resulting in marked haemolytic staining of the intima of both vessels after 20 min. Water and a mixture of blood and water were then injected into the left ventricles in two further pig carcasses, respectively, resulting in haemolytic staining of the intima of the aortic roots, with no staining of the pulmonary trunks. These studies have confirmed that significant hyponatraemia secondary to haemodilution may occur within the left ventricle in freshwater drowning, and that haemolysed blood is capable of causing staining of the aortic root in an animal model. These results provide further data to support haemolytic staining of the aortic root intima as a possible manifestation of freshwater drowning.